// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/files/file_enumerator.h"

#include <stdint.h>
#include <string.h>

#include "base/logging.h"
#include "base/threading/thread_restrictions.h"
#include "base/win/windows_version.h"

namespace base {

// FileEnumerator::FileInfo ----------------------------------------------------

FileEnumerator::FileInfo::FileInfo()
{
    memset(&find_data_, 0, sizeof(find_data_));
}

bool FileEnumerator::FileInfo::IsDirectory() const
{
    return (find_data_.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
}

FilePath FileEnumerator::FileInfo::GetName() const
{
    return FilePath(find_data_.cFileName);
}

int64_t FileEnumerator::FileInfo::GetSize() const
{
    ULARGE_INTEGER size;
    size.HighPart = find_data_.nFileSizeHigh;
    size.LowPart = find_data_.nFileSizeLow;
    DCHECK_LE(size.QuadPart,
        static_cast<ULONGLONG>(std::numeric_limits<int64_t>::max()));
    return static_cast<int64_t>(size.QuadPart);
}

base::Time FileEnumerator::FileInfo::GetLastModifiedTime() const
{
    return base::Time::FromFileTime(find_data_.ftLastWriteTime);
}

// FileEnumerator --------------------------------------------------------------

FileEnumerator::FileEnumerator(const FilePath& root_path,
    bool recursive,
    int file_type)
    : has_find_data_(false)
    , find_handle_(INVALID_HANDLE_VALUE)
    , recursive_(recursive)
    , file_type_(file_type)
{
    // INCLUDE_DOT_DOT must not be specified if recursive.
    DCHECK(!(recursive && (INCLUDE_DOT_DOT & file_type_)));
    memset(&find_data_, 0, sizeof(find_data_));
    pending_paths_.push(root_path);
}

FileEnumerator::FileEnumerator(const FilePath& root_path,
    bool recursive,
    int file_type,
    const FilePath::StringType& pattern)
    : has_find_data_(false)
    , find_handle_(INVALID_HANDLE_VALUE)
    , recursive_(recursive)
    , file_type_(file_type)
    , pattern_(pattern)
{
    // INCLUDE_DOT_DOT must not be specified if recursive.
    DCHECK(!(recursive && (INCLUDE_DOT_DOT & file_type_)));
    memset(&find_data_, 0, sizeof(find_data_));
    pending_paths_.push(root_path);
}

FileEnumerator::~FileEnumerator()
{
    if (find_handle_ != INVALID_HANDLE_VALUE)
        FindClose(find_handle_);
}

FileEnumerator::FileInfo FileEnumerator::GetInfo() const
{
    if (!has_find_data_) {
        NOTREACHED();
        return FileInfo();
    }
    FileInfo ret;
    memcpy(&ret.find_data_, &find_data_, sizeof(find_data_));
    return ret;
}

FilePath FileEnumerator::Next()
{
    base::ThreadRestrictions::AssertIOAllowed();

    while (has_find_data_ || !pending_paths_.empty()) {
        if (!has_find_data_) {
            // The last find FindFirstFile operation is done, prepare a new one.
            root_path_ = pending_paths_.top();
            pending_paths_.pop();

            // Start a new find operation.
            FilePath src = root_path_;

            if (pattern_.empty())
                src = src.Append(L"*"); // No pattern = match everything.
            else
                src = src.Append(pattern_);

            if (base::win::GetVersion() >= base::win::VERSION_WIN7) {
                // Use a "large fetch" on newer Windows which should speed up large
                // enumerations (we seldom abort in the middle).
                find_handle_ = FindFirstFileEx(src.value().c_str(),
                    FindExInfoBasic, // Omit short name.
                    &find_data_,
                    FindExSearchNameMatch,
                    NULL,
                    FIND_FIRST_EX_LARGE_FETCH);
            } else {
                find_handle_ = FindFirstFile(src.value().c_str(), &find_data_);
            }
            has_find_data_ = true;
        } else {
            // Search for the next file/directory.
            if (!FindNextFile(find_handle_, &find_data_)) {
                FindClose(find_handle_);
                find_handle_ = INVALID_HANDLE_VALUE;
            }
        }

        if (INVALID_HANDLE_VALUE == find_handle_) {
            has_find_data_ = false;

            // This is reached when we have finished a directory and are advancing to
            // the next one in the queue. We applied the pattern (if any) to the files
            // in the root search directory, but for those directories which were
            // matched, we want to enumerate all files inside them. This will happen
            // when the handle is empty.
            pattern_ = FilePath::StringType();

            continue;
        }

        FilePath cur_file(find_data_.cFileName);
        if (ShouldSkip(cur_file))
            continue;

        // Construct the absolute filename.
        cur_file = root_path_.Append(find_data_.cFileName);

        if (find_data_.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
            if (recursive_) {
                // If |cur_file| is a directory, and we are doing recursive searching,
                // add it to pending_paths_ so we scan it after we finish scanning this
                // directory. However, don't do recursion through reparse points or we
                // may end up with an infinite cycle.
                DWORD attributes = GetFileAttributes(cur_file.value().c_str());
                if (!(attributes & FILE_ATTRIBUTE_REPARSE_POINT))
                    pending_paths_.push(cur_file);
            }
            if (file_type_ & FileEnumerator::DIRECTORIES)
                return cur_file;
        } else if (file_type_ & FileEnumerator::FILES) {
            return cur_file;
        }
    }

    return FilePath();
}

} // namespace base
